Determine the value of the following complex number power. Your answer will be plotted in orange. $ ({ e^{7\pi i / 4}}) ^ {18} $
Answer: Since $(a ^ b) ^ c = a ^ {b \cdot c}$ $ ({ e^{7\pi i / 4}}) ^ {18} = e ^ {18 \cdot (7\pi i / 4)} $ The angle of the result is $18 \cdot \frac{7}{4}\pi$ , which is $\frac{63}{2}\pi$ $\frac{63}{2}\pi$ is more than $2 \pi$ . It is a common practice to keep complex number angles between $0$ and $2 \pi$ , because $e^{2 \pi i} = (e^{\pi i}) ^ 2 = (-1) ^ 2 = 1$ . We will now subtract the nearest multiple of $2 \pi$ from the angle. $ \frac{63}{2}\pi - 30\pi = \frac{3}{2}\pi $ Our result is $ e^{3\pi i / 2}$.